In 1811, while working for John Jacob Astor's Pacific Fur Company, Ross took part in the founding of Fort Astoria, a fur-trading post at the mouth of the Columbia River.

During the same year he led a detachment up the Columbia River and founded Fort Okanogan where during the winter he was the sole PFC employee at the trading post.

[4] During his solitary posting, Ross' hair greyed from the stress of being socially isolated among the welcoming Syilx people, "savages who had never seen a white man before.

[5] In 1818 Ross acted as scribe for a trading party from the North West Company who traveled within sight of the Teton Range in modern Wyoming.

In 1824, while searching the mountain wilderness of what is present day Idaho, known to them as Columbia District, for beaver, Ross came up the Wood River and discovered Galena Summit on September 18.

Leading a large brigade of Hudson's Bay Company trappers, he wondered if he could get through unknown mountains and rocky defiles that obstructed his passage back to his base of operations at present Challis.

Ross subsequently moved to the Red River Colony, present-day Manitoba, where he served as Sheriff, Post master, and a member of the council.